CN110062690B

CN110062690B - Continuous liquid interface production with force monitoring and feedback

Info

Publication number: CN110062690B
Application number: CN201780067928.3A
Authority: CN
Inventors: R.A.特隆
Original assignee: Carbon Inc
Current assignee: Carbon Inc
Priority date: 2016-12-14
Filing date: 2017-11-28
Publication date: 2021-07-27
Anticipated expiration: 2037-11-28
Also published as: CN110062690A; JP7090614B2; US20210245429A1; EP3554793B1; US10933580B2; US20200180215A1; JP2020501938A; WO2018111533A1; EP3554793A1

Abstract

A method of manufacturing a three-dimensional object (31) by:(a)providing a carrier (15) and an optically transparent member (12) having a build surface, the carrier (15) and the build surface defining a build region therebetween, the optically transparent member (12) carrying a polymerizable liquid (21);(b)advancing the carrier (15) and the optically transparent member (12) away from each other to draw the polymerizable liquid (21) into the build region; then the(c)Optionally, partially retracting the carrier (15) and the optically transparent member (12) towards each other; and then(d)Irradiating the build region with light to form a growing three-dimensional object (31) from the polymerizable liquid (21); and then(e)Periodically repeating steps while maintaining a continuous liquid interface (22) between the growing three-dimensional object (31) and the optically transparent member (12)(b)To(d)Until at least a portion of the three-dimensional object (31) is formed, while during at least some of the periodic repetitions:(i)at the step of advancing(b)During which a momentary increase in the tension of the growing three-dimensional object (31) between the carrier (15) and the building surface is monitored, and optionally during the partial-retraction step(c)During which a momentary increase in compression of the growing three-dimensional object between the carrier (15) and the build surface is monitored; and then, when the transient increase in tension has substantially subsided,(ii)initiating the partial retraction step(c)(when present), or initiating the irradiating step(d)。

Description

Continuous liquid interface production with force monitoring and feedback

RELATED APPLICATIONS

This application claims the benefit of U.S. provisional patent application serial No. 62/433,829, filed 2016, 12, 14, the disclosure of which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates to stereolithography methods and apparatus, particularly those for performing continuous liquid interface production.

Background

J. The results of the experiments by DeSimone et al,Continuous Liquid Interphase PrintingPCT application No. WO2014/1268372 (published 2014-8-21; see also U.S. patent No. 9,205,601) describes an improved stereolithography process from a window in which adhesion to the window is inhibited by passing a polymerization inhibitor, such as oxygen or a base, through the window (or out of a "pool" within the window) thereby forming a non-polymeric release layer or "dead zone" which forms a "liquid interface" with the growing three-dimensional object, thereby allowing the three-dimensional object to be produced continuously or without layers from the interface (see also j. Tumbleston et al, Continuous liquid interface production of 3D Objects,Science 347, 1349-. Other methods for performing continuous liquid interface production (or "CLIP") include: oxygen is generated as an inhibitor by electrolysis using a liquid interface comprising immiscible liquids (see l. Robeson et al, WO 2015/164234, published on 10/29/2015), oxygen is generated as an inhibitor (see i. Craven et al, WO 2016/133759,published 8/25/2016), and incorporation of magnetically-localizable particles coupled with photoactivators into polymerizable liquids (see j. Rolland, WO 2016/145182, published 9/15/2016).

In Ermoshkin et al,Three-Dimensional Printing with Reciprocal Feeding of Polymerizable LiquidPCT application publication No. WO 2015/195924 (published on 12/23/2015) describes a CLIP method in which a carrier is advanced in a step-wise or interactive fashion to facilitate flow of a viscous polymerizable liquid into a build area (see, in particular, fig. 22-25 and 27A-29B and associated text therein).

One advantage of CLIP is the speed at which objects can be manufactured. Another advantage of CLIP is the variety of (usually viscous) polymerizable liquids that can be used in the process, such as the "dual cure" resins described in j. Rolland et al, U.S. patent No. 9,453,142 (and others). However, in some cases, the intermediate three-dimensional object formed by such resins is itself flexible rather than rigid due to the inherent flexibility of the material. In other cases, due to the geometry of the object, the intermediate body may be relatively rigid early in the production of the object, but the object may become increasingly flexible (or "compliant") as production progresses. In cases like these, the produced compliant object may not be able to overcome the fluid adhesion of the object to the build surface and cause fluid to flow into the build zone (particularly during step-wise or interactive modes of operation).

Another potential complication in speeding up production is premature photoactivation. If the exposure is prematurely activated in step mode while the resin is still flowing into the build area, uncured internal resin channels in the object (observable as surface pitting on the object) may occur. And if the exposure is prematurely activated in the interaction mode while the resin is flowing out of the build area, blooming or fuzzing of the object surface (sometimes referred to as "edge phenomenon") may occur. Therefore, new methods of conducting continuous liquid interface production are needed.

Disclosure of Invention

A first aspect of the invention is a method of manufacturing a three-dimensional object byThe method comprises the following steps:(a)providing a carrier and an optically transparent member having a build surface, the carrier and the build surface defining a build region therebetween, the optically transparent member carrying a polymerizable liquid;(b)advancing the carrier and the optically transparent member away from each other to draw the polymerizable liquid into the build area; then the(c)Optionally, partially retracting the carrier and the optically transparent member towards each other; and then(d)Illuminating the build area with light to form a growing three-dimensional object from the polymerizable liquid; and then(e)Periodically repeating the steps while maintaining a continuous liquid interface between the growing three-dimensional object and the optically transparent member(b)To(d)Until at least a portion of the three-dimensional object is formed, while during at least some of the periodic repetitions:(i)in the advancing step(b)During which the instantaneous increase in tension of the growing three-dimensional object between the carrier and the building surface is monitored, and optionally in a partial retraction step(c)During which a transient increase in compression of the grown three-dimensional object between the carrier and the build surface is monitored; and then, when the transient increase in tension has substantially subsided,(ii)beginning a partial retraction step(c)(when present), or initiating the irradiating step (d). In some embodiments, there is no partial retraction step during at least some of the periodic repetitions(c)(ii) a In other embodiments, there is a partial retraction step during at least some of the periodic repetitions(c). In some embodiments, the method further comprises, during at least some of the periodic repetitions:(iii)at the partial retraction step(c)During which a transient increase in compression of the grown three-dimensional object between the carrier and the build surface is monitored; and then, when the transient increase in compression has substantially subsided,(iv)starting the irradiation step(d)。

Another aspect of the invention is a method of manufacturing a three-dimensional object by:(a)providing a carrier and an optically transparent member having a build surface, the carrier and the build surface defining a build region therebetween, the optically transparent member carrying a polymerizable liquid;(b)advancing the carrier and the optically transparent member away from each other to move the carrier and the optically transparent member away from each otherDrawing a polymerizable liquid into the build zone; then the(c)Partially retracting the carrier and the optically transparent member toward each other; and then(d)Illuminating the build area with light to form a growing three-dimensional object from the polymerizable liquid; and then(e)Periodically repeating the steps while maintaining a continuous liquid interface between the growing three-dimensional object and the optically transparent member(b)To(d)Until at least a portion of the three-dimensional object is formed, while during at least some of the periodic repetitions:(i)optionally, during the advancing step(b)During which the instantaneous increase in tension of the growing three-dimensional object between the carrier and the building surface is monitored, and optionally in a partial retraction step(c)During which a transient increase in compression of the grown three-dimensional object between the carrier and the build surface is monitored; and then, when the transient increase in tension has substantially subsided,(ii)optionally, a partial retraction step is initiated(c)(when present), or initiating an irradiation step(d)(ii) a Then the(iii)At the partial retraction step(c)During which a transient increase in compression of the grown three-dimensional object between the carrier and the build surface is monitored; and then, when the transient increase in compression has substantially subsided,(iv)starting the irradiation step(d)。

In some embodiments of the foregoing, in(f)The continuously advancing carrier and the optically transparent member are moved away from each other and(g)at least a portion of the three-dimensional object is formed when the build area is intermittently or continuously irradiated to form the grown three-dimensional object while maintaining the continuous liquid interface.

In some embodiments of the foregoing, at least a portion of the grown three-dimensional object is flexible (due to the flexibility of the solidified material, the geometry of the object, or a combination thereof).

In some embodiments of the foregoing, at least a portion (e.g., a major portion) of the object is in the form of a lattice or a mesh.

In some embodiments of the foregoing, the polymerizable liquid is viscous (e.g., has a viscosity of at least 200, 300, 1,000, or 2,000 centipoise or more at room temperature) at room temperature (e.g., 25 degrees celsius).

In some embodiments of the foregoing, the optically transparent member comprises a semipermeable member (e.g., a fluoropolymer), and the advancing, partially retracting (when present), irradiating, and/or periodically repeating steps are performed while simultaneously:

(i) dead space for continuously maintaining polymerizable liquid in contact with build surface, and/or

(ii) Continuously maintaining a gradient of polymerization zones between and in contact with each of the dead zones and the growing three-dimensional object, the gradient of polymerization zones comprising a polymerizable liquid in partially cured form,

and continuous maintenance of the dead zone is performed by feeding the polymerization inhibitor through the optically transparent member, thereby creating a gradient of inhibitor in the dead zone and optionally in at least a portion of the gradient of the polymerization zone. For example, in some embodiments, the polymerizable component comprises a free-radically polymerizable liquid, and the inhibitor comprises oxygen; in other embodiments, the polymerizable component comprises an acid-catalyzed polymerizable liquid or a cationically polymerizable liquid, and the inhibitor comprises a base.

In some embodiments of the foregoing, the three-dimensional object is fabricated at a speed of at least 1 or 10 millimeters per hour to 1,000 or 10,000 millimeters per hour or more.

Another aspect of the invention is an apparatus useful for making a three-dimensional object from a polymerizable liquid, the apparatus comprising:(a)a carrier on which a three-dimensional object can be fabricated;(b)an optically transparent member having a build surface operatively associated with a carrier, the carrier and build surface defining a build region therebetween, the optically transparent member configured to carry a polymerizable liquid;(c)an elevator assembly in operative association with the carrier and/or the optically transparent member, the elevator assembly configured for advancing the carrier and the optically transparent member away from each other to draw polymerizable liquid into the build area;(d)a light engine operatively associated with the optically transparent member and positioned to illuminate the build area with light to form a grown three-dimensional object from the polymerizable liquid; (e) a force sensor operatively associated with the carrier and/or the optically transparent member and configured to monitor formation between the carrier and the build surface therebetweenA transient increase in tension and/or a transient increase in compression of the three-dimensional object; and (f) a controller in operative association with the elevator assembly, the light engine, and the force sensor, wherein the controller is configured for advancing the carrier and the build surface away from each other, then optionally partially retracting the carrier and the build surface toward each other, and then illuminating the build area with light to form a periodically repeating cycle of the three-dimensional object therebetween, while maintaining a continuous liquid interface between the three-dimensional object and the optically transparent member, until at least a portion of the three-dimensional object is formed, the controller further configured to, during at least some of the periodic repetitions:(i)monitoring a transient increase in tension of the growing three-dimensional object between the carrier and the build surface during the advancing, optionally a transient increase in compression of the growing three-dimensional object between the carrier and the build surface during the partial retracting; and then, when the transient increase in tension has substantially subsided, initiating partial retraction (when present), or initiating irradiation; and/or(ii)Monitoring a transient increase in compression of the grown three-dimensional object between the carrier and the build surface during the partial retraction; and then, when the transient increase in compression has substantially subsided, initiating the irradiating step. In some embodiments, the optically transparent member comprises a semipermeable member (e.g., a fluoropolymer). In some embodiments, the light engine includes a light source (e.g., a laser) in combination with a patterned array (e.g., a liquid crystal display array or a digital micromirror array). In some embodiments, the force sensor comprises a strain gauge.

The step of monitoring the transient increase in tension may be performed by:(a)the absolute force is monitored and the absolute force is monitored,(b)monitoring the rate of change of force, or(c)Both the absolute force and the rate of change of the force are monitored in conjunction with each other. In some embodiments, preference is given to(b)Or(c)To reduce the effect of slow zero drift, as discussed below.

Lin et al/Autodesk, U.S. patent application publication No. 2015/0331402 (11/19/2015) describes, in paragraph 0032- & 0033, strain gauges embedded in DLP SLA systems for measuring window adhesion, and for measuring compressive, tensile, shear, bending and torsional stresses during printing, but does not suggest the use of the strain gauges in connection with manufacturing elastic intermediates or during step or interactive printing modes, and does not indicate how such information can be used to eliminate time loss during such modes.

The invention is explained in more detail in the figures herein and in the description set forth below. The disclosures of all U.S. patent references cited herein are incorporated by reference in their entirety.

Brief Description of Drawings

Figure 1 schematically shows an apparatus that can be used to carry out the invention. The larger upward arrow indicates the dominant direction of upward movement during step and interactive (or "pumping") production mode. The dashed arrow indicates less downward movement during the interaction mode.

Figure 2 schematically illustrates the force sensor and control assembly of one embodiment of the apparatus of the present invention.

Fig. 3 schematically shows components (or operations) implemented in (or by) a controller (microcontroller) of one embodiment of the apparatus of the present invention.

FIG. 4 shows the step control elements of one embodiment of the apparatus of the present invention, but without force feedback.

FIG. 5 shows the step control elements of the embodiment of FIG. 4, but now implementing force feedback.

Figure 6 shows the interactive control elements of one embodiment of the apparatus of the present invention, but without force feedback.

FIG. 7 shows the interactive control elements of the embodiment of FIG. 6, but now implementing force feedback.

Fig. 8 shows the forces induced in a step-wise operating mode of Continuous Liquid Interface Production (CLIP), with force monitoring, but without feedback.

Fig. 9 illustrates a step mode of operation of the CLIP of fig. 8, but with force feedback implemented to reduce the time otherwise lost.

Fig. 10 shows forces induced in the CLIP's interoperation mode with force monitoring but without feedback.

Fig. 11 illustrates the CLIP's interactive mode of operation of fig. 10, but with force feedback implemented (for both tension and compression) to reduce the time that would otherwise be lost.

Fig. 12 graphically compares the measurement of absolute force (thin lines with circles) with the measurement of the rate of change of force (thick lines with squares).

FIG. 13 is similar to FIG. 3, but utilizes the rate of change of force as a force measurement.

FIG. 14 is similar to FIG. 7, but utilizes the rate of change of force as a force measurement.

Detailed description of illustrative embodiments

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Like numbers refer to like elements throughout. In the drawings, the thickness of certain lines, layers, components, elements or features may be exaggerated for clarity. The use of dashed lines illustrates optional features or operations unless specified otherwise.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components, and/or groups, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups, or combinations thereof.

As used herein, the term "and/or" includes any and all possible combinations or one or more of the associated listed items, as well as the absence of a combination when interpreted with an alternative word ("or").

Unless defined otherwise, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and claims, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.

It will be understood that when an element is referred to as being "on," "attached" to, "connected" to, "coupled" with, "contacting" another element, etc., another element, it can be directly on, attached to, connected to, coupled with, and/or contacting the other element, or intervening elements may also be present. In contrast, when an element is referred to as being, for example, "directly on," "directly attached" to, "directly connected" to, "directly coupled" with or "directly contacting" another element, there are no intervening elements present. Those skilled in the art will also appreciate that references to a structure or feature that is disposed "adjacent" another feature may have portions that overlap or underlie the adjacent feature.

Spatially relative terms, such as "under", "below", "lower", "on", "upper", and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device is turned over in the figures, elements described as "under" or "beneath" other elements or features would then be oriented "over" the other elements or features. Thus, the exemplary term "under …" can encompass both an orientation above and below …. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. Similarly, the terms "upward," "downward," "vertical," "horizontal," and the like are used herein for explanatory purposes only, unless explicitly indicated otherwise.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. Rather, these terms are only used to distinguish one element, component, region, layer and/or section from another element, component, region, layer and/or section. Thus, a first element, component, region, layer or section discussed herein could be termed a second element, component, region, layer or section without departing from the teachings of the present invention. The sequence of operations (or steps) is not limited to the order presented in the claims or figures unless specifically indicated otherwise.

1. General method and apparatus

As noted above, methods, apparatus and polymerizable liquids or resins for "continuous liquid interface production" (or "CLIP") are described in, for example, j. DeSimone et al, PCT application No. PCT/US2014/015486 (published as U.S. patent No. 9,211,678); PCT/US2014/015506 (published as U.S. patent No. 9,205,601), PCT/US2014/015497 (published as U.S. patent No. 9,216,546), J. Tumbleston et al,Continuous liquid interface production of 3D Objects，Science 347, 1349-,Proc. Natl. Acad. Sci. USA 113, 11703-. Other methods for performing continuous liquid interface production (or "CLIP") include: oxygen is generated as an inhibitor by electrolysis using a liquid interface comprising immiscible liquids (see l. Robeson et al, WO 2015/164234, published 10/29/2015) (see i. Craven et al)WO 2016/133759, published 25/8/2016), and incorporation of magnetically localizable particles coupled to a photoactivator into a polymerizable liquid (see j. Rolland, WO 2016/145182, published 15/9/2016). Still other methods are described in U.S. patent application publication numbers 2017/0129169 (Batchelder et al) and 2016/0288376 (Sun et al).

In addition, and as also indicated above, methods and apparatus for implementing CLIP using stepwise or reciprocal advancement of a carrier and a growing three-dimensional object away from an optically transparent member or "window" are described, for example, in a. Ermoshkin et al,Three-Dimensional Printing with Reciprocal Feeding of Polymerizable LiquidPCT application publication No. WO 2015/195924 is known and described.

Dual cure polymerizable liquids useful in CLIP are known and described in, for example, J. Rolland et al, PCT application PCT/US2015/036893 (see also U.S. patent application publication No. US 2016/0136889), PCT/US2015/036902 (see also U.S. patent application publication No. US 2016/0137838), PCT/US2015/036924 (see also U.S. patent application publication No. US 2016/016077), and PCT/US2015/036946 (see also U.S. patent No. 9453,142).

2. Implementation with force feedback

As noted above, fig. 1 schematically illustrates an apparatus that may be used to carry out the present invention. The larger upward arrow indicates the dominant direction of upward movement during step and interactive (or "pumping") production mode. The dashed arrow indicates less downward movement during the interaction mode. In general, the apparatus includes a light engine 11, a window (or "build plate") 12, a controller 13, and a lift and drive assembly 14. A carrier platform (or "carrier plate") 15 is mounted to the elevator and drive assembly as in conventional equipment, but has a force sensor 16 operatively associated therewith. A polymerizable liquid 21 is provided on top of the window 12.

The window 12 may be impermeable or semi-permeable to the polymerization inhibitor (e.g., oxygen) depending on the particular process employed to effect continuous liquid interface production. In some embodiments, the window comprises a fluoropolymer, according to known techniques.

The grown three-dimensional object 31 is shown formed between the carrier platform 15 (to which it is adhered) and the polymerizable liquid 21 with a continuous liquid interface 22 between the polymerizable liquid 21 and the object 31. Areas with higher rigidity (rigid areas) 32 and areas with lower rigidity (flexible areas) 33 are indicated on the growing object. As the schematic illustration indicates, the flexible regions are those that are highly cantilevered and formed later in the process, but in other embodiments (e.g., highly reticulated objects and/or objects formed from resins that are inherently flexible when cured), the entire object may be flexible.

Any suitable light engine 11 may be used, including any of a variety of light sources and/or patterning elements, including lasers (e.g., scanning lasers as in conventional stereolithography), Liquid Crystal Display (LCD) panels, Digital Micromirror Displays (DMDs), and the like. A single light engine may be used, or a set of tiled light engines may be used, depending on the size of the window 12 and the desired resolution.

Although the schematic shows that the advance-away is achieved by lifting the carrier on an elevator, it is also noted that the advance-away and partial retraction can be achieved by providing a fixed or stationary carrier and mounting a window and light engine (which can then be lowered) on the elevator below the carrier.

Any suitable device may be used as force sensor 16. Examples include, but are not limited to, mechanical tactile sensors, capacitive force sensors, metal strain gauges, semiconductor strain gauges, conductive elastomers, carbon felt and carbon fiber sensors, piezoelectric force sensors, thermoelectric force sensors, optical force sensors, magnetic force sensors, ultrasonic force sensors, electrochemical force sensors, and the like, including combinations thereof. See for example Matthias fastser,Force Sensing Technologies(Federal Industrial science, Zurich, Switzerland, spring school of 2010). One suitable example is the Omega LCM202-1KN miniature metric universal load cell available from Omega Engineering corporation (800 Connecticut Ave., Suite 5N01, Norwalk, Connecticut 06854 USA). Any suitable configuration of force or load cell may be used, including but not limited to on-carrier and load cellA single load cell mounted in-line (or "sandwiched" between) between the elevators. The force sensors may include multiple force sensors to provide an averaged output (e.g., sandwiched between compression plates to balance the load) and/or may include multiple force sensors to provide independent data from multiple regions of the carrier. Additionally, force sensing may be performed by sensing motor current or torque, or any other direct or indirect measurement of force.

Further details of structuring non-limiting embodiments of the apparatus of the invention for carrying out the methods described herein are given in FIGS. 2-7. In this illustrative embodiment, communication between the microcontroller and the main system controller (which may be local or remote, e.g., cloud-based) is not shown. In the illustrative embodiment, whenever the move, wait, or expose functions are invoked, they are directed by the high-level host system controller and executed by the microcontroller. Naturally, the entire control procedure may alternatively be implemented by the main system controller or the local controller.

As generally shown in FIG. 2, the force sensor 16, which is an analog device, is digitally sampled by a microcontroller having an analog-to-digital converter (ADC; 13a) and the information is stored in microcontroller memory 13 b. The microcontroller preferably maintains a constant sampling rate for the ADC and analog devices. The microcontroller handles all movement, wait and light engine functions. In the absence of force feedback (which may also be used in combination with force feedback in the present invention), a pre-calculated command table is given to the microcontroller by the advanced system controller. With force feedback, the microcontroller may be instructed to move and wait with feedback, rather than using a fixed pre-calculated wait command. The microcontroller may be encoded using any logic language, including but not limited to C/C + +.

Fig. 3 shows other components (or operations) implemented in (or by) the microcontroller. The advanced system controller informs the microcontroller to move, wait, and monitor the force sensor for triggers (triggers). Negative force is depicted in the figure as "tension"; the positive force is depicted as "compression" in the figure.

FIG. 4 shows the step control elements of one embodiment of the apparatus of the present invention, but without force feedback implemented, and FIG. 5 shows the step control elements of the embodiment of FIG. 4, but now with force feedback implemented. As noted previously, all cycles in the production of the object may utilize force feedback, or some cycles may forego force feedback (e.g., for the production of an early segment of the object, or production with highly predictable portions of behavior). In a similar fashion, FIG. 6 shows the interactive control elements of one embodiment of the apparatus of the present invention, but without force feedback implemented, and FIG. 7 shows the interactive control elements of the embodiment of FIG. 6, but now with force feedback implemented. Some or all of the aforementioned modes of operation may be combined together during production of a particular object, and indeed some portions of the object may be manufactured in a "continuous" mode of operation.

In general, the process of the invention may be carried out as follows, with the presence or absence of optional steps depending on(i)Whether force feedback is implemented during stepwise or interactive carrier propulsion, and(ii)whether force feedback is implemented during the upstroke, the downstroke, or both the upstroke and the downstroke of a particular cycle. In this regard, the steps of various embodiments may generally include:

(a)first, a carrier and an optically transparent member having a build surface are provided, the carrier and the build surface defining a build region therebetween, the optically transparent member carrying a polymerizable liquid.

(b)The foregoing is provided and the method begins by advancing the carrier and optically transparent member away from each other to draw polymerizable liquid into the build area. The advance distance is not critical, but is generally considered with the subsequent partial advance steps, and the cumulative distance of advance (sometimes also referred to as the "slice thickness") may be 0.1 or 0.2 millimeters, up to 20 or 40 millimeters, or more. The next step may immediately follow, or there may be a short pause (e.g., 0.1 or 1 second to 5, 10, 100, or 300 seconds or more, such as a "plateau" between advancement and partial retraction in interaction mode, or simply a pause between advancement and irradiation in step mode).

(c)Optionally, but preferably in some embodiments, after the foregoing advancing step, allowingThe carrier and the optically transparent member are partially retracted towards each other (either immediately after the advancing step (without delay) or after a pause as described above).

(d)In the advancing step(b)And optionally a retraction step(c)The build area is then illuminated with light to form a growing three-dimensional object from the polymerizable liquid. The irradiation may be for any suitable duration, such as 0.1 or 0.5 seconds to 10, 20, 50 or 100 seconds or more. The next step (periodic return to step)(b)) This may be immediately followed, or may be followed after a pause, as discussed below.

(e)In the step of irradiation(d)Thereafter (e.g., immediately after irradiation (no delay), or after a delay of 0.1 to 1, 10, or 100 seconds), the steps are periodically repeated while maintaining a continuous liquid interface between the growing three-dimensional object and the optically transparent member(b)To(d)(e.g., another 5 or 10 times, to another 5,000 or 10,000 times or more) until at least a portion of the three-dimensional object is formed.

During at least some of the aforementioned periodic repetitions, the following steps are further preformed:

(i)optionally, but preferably in some embodiments, at the advancing step(b)During which the instantaneous increase in tension of the growing three-dimensional object between the carrier and the building surface is monitored, and optionally in a partial retraction step(c)During which a transient increase in compression of the grown three-dimensional object between the carrier and the build surface is monitored; and then, when the transient increase in tension has substantially subsided,

(ii)optionally, but preferably in some embodiments, a partial retraction step is initiated(c)(when present), or initiating an irradiation step(d)(ii) a Then the

(iii)At the partial retraction step(c)During which a transient increase in compression of the grown three-dimensional object between the carrier and the build surface is monitored; and then, when the transient increase in compression has substantially subsided,

(iv)starting the irradiation step(d)。

The times and distances given above are not critical and are for illustrative purposes only. The particular time and distance will depend on factors such as: object geometry, irradiation wavelength and intensity, object resolution requirements, resin properties (including but not limited to photoinitiator type and density, resin viscosity, and post-irradiation polymeric resin properties), operating temperature, etc., and may be optimized by one skilled in the art. When referring to a transient increase (or decrease) in tension (or compression, "substantially subside" generally means within five, ten, or twenty percent of the immediately preceding tension or compression. Typically, the total or average speed of the manufactured object or relevant portion thereof is at least 1 or 10 millimeters per hour, up to 1,000 or 10,000 millimeters per hour or more.

Fig. 8 shows a step-wise mode of operation for Continuous Liquid Interface Production (CLIP), with force monitoring, but without feedback. Fig. 9 shows essentially the same mode of operation, but this time with force feedback, used to start the next exposure or illumination step during the periodic repetition of the steps. The upward arrows indicate the general time and direction of carrier movement during the advancing step. Note the reduction in time to complete the three cycles in fig. 9 compared to fig. 8.

Fig. 10 shows the interactive mode of operation of CLIP with force monitoring but without feedback. Fig. 11 illustrates the CLIP's interactive mode of operation of fig. 10, but with force feedback implemented (for both tension and compression) to begin the partial retraction step first after each advancement step, and to begin the illumination step second after each partial retraction step. The larger upward arrow indicates the approximate time and predominantly upward direction of carrier movement during the advancing step, and the downward arrow indicates the approximate time and less downward movement of carrier movement during the partial retracting step. Note the reduction in time to complete the three cycles in fig. 11 compared to fig. 10.

In some embodiments, a benefit of force sensor feedback is that it allows for more efficient printing of elastic objects. For example, the rigidity or elasticity of the object being manufactured or a part thereof need not be known. The object need only be rigid enough to (a) withstand the forces of production without tearing or breaking of the part, and (b) overcome the fluid forces of the resin to achieve the desired level of each exposure or shot. Without feedback as described herein, the solution may be complicated and difficult to validate a Finite Element Analysis (FEA) model that simulates the stiffness, deformation, and adhesion, and the actual distance or height required to advance the carrier to overcome the adhesion (i.e., "pump" the resin into the build area). The results of such an approach will generally be conservative, as such simulations are difficult to perfect, especially when the process input data is inconsistent. In contrast, the methods described herein allow for a more invasive approach to reduce the amount of time that would otherwise be wasted during each exposure cycle.

In some embodiments, when measuring absolute forces, there may be a slow drift of zero (lack of tension or compression) over time. Without wishing to be bound by any particular theory, this may be due to, for example, increased weight of the carrier platform as additional resin is polymerized to the carrier, as the component builds in the Z (vertical) direction, buoyancy changes, electronic sensor nonlinearities, and the like. While the drift of the zero point can be tracked by various techniques, one solution is to track the force using the rate of change of the force (equivalent to the slope, see fig. 12), as shown in fig. 13-14. Again, the functions may be implemented in a microcontroller, where the advanced system controller notifies the microcontroller to move, wait, monitor triggers of the force sensor, and so forth.

Implementing force sensing based on rate of change provides one possible feedback solution. However, this technique loses some of the fault-tolerant aspects of monitoring absolute force. Thus, a still more robust technique is to use the absolute force and the rate of change of the force in combination as a force sensing technique.

The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. The invention is defined by the claims and the equivalents of the claims included therein.

Claims

1. A method of manufacturing a three-dimensional object, the method comprising the steps of:

(a)provide forA carrier and an optically transparent member having a build surface, the carrier and the build surface defining a build region therebetween, the optically transparent member carrying a polymerizable liquid;

(b)advancing the carrier and the optically transparent member away from each other to draw the polymerizable liquid into the build region; then the

(c)Optionally, partially retracting the carrier and the optically transparent member towards each other; and then

(d)Illuminating the build area with light to form a growing three-dimensional object from the polymerizable liquid; and then

(e)Periodically repeating steps while maintaining a continuous liquid interface between the growing three-dimensional object and the optically transparent member(b)To(d)Until at least a portion of the three-dimensional object is formed, while during at least some of the periodic repetitions:

(i)at the step of advancing(b)During which a momentary increase in tension of the growing three-dimensional object between the carrier and the build surface is monitored, and optionally at the partial retraction step(c)During which a transient increase in compression of the grown three-dimensional object between the carrier and the build surface is monitored; and then, when said transient increase in tension has substantially subsided,

(ii)initiating the partial retraction step(c)Or starting the irradiating step(d)。

2. The method of claim 1, wherein the step of monitoring for a transient increase in tension is performed by:(a)the absolute force is monitored and the absolute force is monitored,(b)monitoring the rate of change of force, or(c)Both the absolute force and the rate of change of the force are monitored in conjunction with each other.

3. The method of claim 1, wherein the step of monitoring the transient increase in tension is performed by monitoring both the absolute force and the rate of change of force in conjunction with each other.

4. The method of claim 1, wherein during at least some of the periodic repetitions, there is no partial retraction step(c)。

5. The method of claim 1, wherein during at least some of the periodic repetitions, there is the partial retraction step(c)。

6. The method of claim 5, further comprising, during at least some of the periodic repetitions:

(iii)at the partial retraction step(c)During which a transient increase in compression of the grown three-dimensional object between the carrier and the build surface is monitored; and then, when said transient increase in compression has substantially subsided,

(iv)starting the irradiating step(d)。

7. The method of any one of claims 1-5, wherein at least a portion of the grown three-dimensional object is formed while continuously advancing the carrier and the optically transparent member away from each other and intermittently or continuously illuminating the build region to form the grown three-dimensional object while maintaining the continuous liquid interface.

8. The method of any one of claims 1-5, wherein at least a portion of the grown three-dimensional object is flexible.

9. The method of any one of claims 1-5, wherein at least a portion of the three-dimensional object and/or the grown three-dimensional object is in the form of a grid or mesh.

10. The method of any one of claims 1-5, wherein the polymerizable liquid is viscous at ambient or room temperature.

11. The method of any one of claims 1-5, wherein:

the optically transparent member comprises a semi-permeable member, and the advancing, partially retracting, irradiating, and/or periodically repeating steps are performed while simultaneously:

(i) a dead zone for continuously maintaining polymerizable liquid in contact with the build surface, and/or

(ii) Continuously maintaining a gradient of polymerization zones between and in contact with each of said dead zones and said growing three-dimensional object, said gradient of polymerization zones comprising a polymerizable liquid in partially cured form,

and said continuous maintenance of dead zones is performed by feeding polymerized inhibitor through said optically transparent member, thereby creating a gradient of inhibitor in said dead zones and optionally in at least a portion of said gradient of polymerization zones.

12. The method of claim 11, wherein:

the polymerizable liquid comprises a free-radically polymerizable liquid, and the inhibitor comprises oxygen; or

The polymerizable liquid comprises an acid-catalyzed polymerizable liquid or a cationically polymerizable liquid, and the inhibitor comprises a base.

13. The method of any one of claims 1-5, wherein the three-dimensional object is fabricated at a rate of at least 1 millimeter per hour to 10,000 millimeters per hour.

14. A method of manufacturing a three-dimensional object, the method comprising the steps of:

(a)providing a carrier and an optically transparent member having a build surface, the carrier and the build surface defining a build region therebetween, the optically transparent member carrying a polymerizable liquid;

(b)advancing the carrier and the optically transparent member away from each other to draw the polymerizable liquid intoThe construction region; then the

(c)Partially retracting the carrier and the optically transparent member toward each other; and then

(d)Illuminating the build area with light to form a growing three-dimensional object from the polymerizable liquid; and then;

(i)optionally, during said advancing step(b)During which a momentary increase in tension of the growing three-dimensional object between the carrier and the build surface is monitored, and optionally at the partial retraction step(c)During which a transient increase in compression of the grown three-dimensional object between the carrier and the build surface is monitored; and then, when said transient increase in tension has substantially subsided,

(ii)optionally, initiating the partial retraction step(c)Or starting the irradiation step(d)(ii) a Then the

(iv)starting the irradiating step(d)。

15. The method of claim 14, wherein the method is carried out in(f)Continuously advancing the carrier and the optically transparent member away from each other and(g)forming at least a portion of the three-dimensional object while intermittently or continuously irradiating the build region to form the grown three-dimensional object while maintaining the continuous liquid interface.

16. The method of claim 14 or 15, wherein at least a portion of the grown three-dimensional object is flexible.

17. The method of claim 14 or 15, wherein at least a portion of the three-dimensional object and/or the grown three-dimensional object is in the form of a grid or mesh.

18. The method of claim 14 or 15, wherein the polymerizable liquid is viscous at ambient or room temperature.

19. The method of claim 14 or 15, wherein:

20. The method of claim 19, wherein:

21. The method of claim 14 or 15, wherein the three-dimensional object is fabricated at a rate of at least 1 millimeter per hour to 10,000 millimeters per hour.

22. An apparatus useful for fabricating a three-dimensional object from a polymerizable liquid, the apparatus comprising:

(a)a carrier on which a three-dimensional object can be fabricated;

(b)an optically transparent member having a build surface operatively associated with the carrier, the carrier and the build surface defining a build region therebetween, the optically transparent member configured to carry a polymerizable liquid;

(c)an elevator assembly in operative association with the carrier and/or the optically transparent member, the elevator assembly configured to advance the carrier and the optically transparent member away from each other to draw the polymerizable liquid into the build region; then the

(d)A light engine operatively associated with the optically transparent member and positioned to illuminate the build region with light to form a grown three-dimensional object from the polymerizable liquid;

(e) a force sensor operatively associated with the carrier and/or the optically transparent member and configured to monitor a transient increase in tension and/or a transient increase in compression of a three-dimensional object formed therebetween between the carrier and the build surface; and

(f) a controller in operative association with the elevator assembly, the light engine, and the force sensor, wherein the controller is configured to, while maintaining a continuous liquid interface between the three-dimensional object and the optically transparent member, for advancing the carrier and the build surface away from each other, then optionally partially retracting the carrier and build surface toward each other, and then illuminating the build area with light to form a periodically repeating cycle of three-dimensional objects therebetween until at least a portion of the three-dimensional object is formed, the controller being further configured to, during at least some of the periodically repeating cycles:

(i)monitoring the load during the propulsionA transient increase in tension of the grown three-dimensional object between the body and the build surface, optionally monitoring a transient increase in compression of the grown three-dimensional object between the carrier and the build surface during the partial retraction; and then, when said transient increase in tension has substantially subsided, initiating said partial retraction, or initiating said irradiation; and/or

(ii)Monitoring a transient increase in compression of the growing three-dimensional object between the carrier and the build surface during the partial retraction; and then, when the transient increase in compression has substantially subsided, initiating the irradiation.

23. The apparatus of claim 22, wherein the optically transparent member comprises a semi-permeable member.

24. The apparatus of claim 22 or 23, wherein the light engine comprises a light source in combination with a patterned array.

25. The apparatus of claim 22 or 23, wherein the force sensor comprises a strain gauge.